Printer Friendly

Absolute surface coverage measurement demonstrated using vibrational overtones.

Using evanescent-wave cavity ring-down spectroscopy (EW-CRDS), a technique pioneered at NIST, measurement of absolute surface coverage with submonolayer sensitivity has been demonstrated. The first C-H stretching overtones of trichloroethylene (TCE), cis-dichloroethylene, and trans-dichloroethylene were probed for the gas- and adsorbed-phase species using a seeded optical parametric amplifier. Polarized absolute adsorbate spectra were obtained by EW-CRDS using a high-finesse fused-silica monolithic optical resonator, while absolute absorption cross sections for the gasphase species were determined by conventional CRDS. A measure of the average transition moment orientation on the surface, which is required for monolayer coverage determination, was derived from the polarization anisotropy of the surface spectra. As the vector-character of absorption yields only an average tilt angle to characterize the orientation distribution, the method is accurate for highly oriented, unimodal surface distributions. For such well-ordered systems, coverage uncertainties of [+ or -]0.1 monolayer are possible. The EW-CRDS technique also was shown to provide a significant advance in sensitivity for chemical detection of TCE, which is a major environmental contaminant.

This work, performed collaboratively by NIST and the Eindhoven University of Technology in the Netherlands, has been supported by the Environmental Management Science Program of the Department of Energy.

CONTACT: Andrew Pipino, (301) 975-2565; andrew.pipino@nist.gov.
COPYRIGHT 2003 National Institute of Standards and Technology
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2003, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

 Reader Opinion

Title:

Comment:



 

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:News Briefs
Publication:Journal of Research of the National Institute of Standards and Technology
Date:Sep 1, 2003
Words:205
Previous Article:Subscriptions to online Journal of Physical and Chemical Reference Data increase greatly.
Next Article:New CD-ROM released.


Related Articles
Shaking up quasicrystals.
The polar nanostructure of novel relaxor ferroelectric materials. (News Briefs).
Brillouin light scattering. (News Briefs).
Pulsed laser range finders. (Instruments).
Thermal conductivity measurement of an electron-beam physical-vapor-deposition coating.
Studies performed of acoustic loss in langasite, langatate, and langanite.
Lone protein molecule could tip this scale.
Just measure something! start with basic objectives that show the value of public relations.
Infrared spectroscopy in the analysis, characterization, and testing of coatings.
Raman spectroscopy in coatings research and analysis: Part I. Basic principles.

Terms of use | Copyright © 2014 Farlex, Inc. | Feedback | For webmasters